On his show last night, Conan O'Brien, who grew up in the city, said, "I just wanted to take a moment to say that, like everyone here, my thoughts and prayers are with the people of Boston and everybody who's been affected by this absolutely senseless act."

Ellen DeGeneres closed out the taping of her show (which airs today) by sending her well-wishes. "Before we end the show today, I want to tell everyone in Boston that we're thinking about you. We're watching the news and it is incredibly sad. As we're taping, we're still learning new details. And please know that you're in our hearts. Be kind to one another."

But fellow late-night host Craig Ferguson took on an angrier tone. "Is anyone else sick of this sh--?" he asked. "I seem to have to say that too often."

Ferguson also spoke about his special connection to Boston.

"When I became an American citizen in 2008, I spoke at Faneuil Hall on July 4," he recounted. "My first stand-up special in America, I shot it in Boston. I like that town. I'm appalled by this thing, and when I watch it on these streets that I know, it's horrifying."

Other late-night hosts -- Jay Leno, David Letterman, and Jimmy Fallon -- were off this week.